WAKING EFFECTIVENESS OF VISUAL ALERTING SIGNALS

People who are unable to hear acoustic alarm signals because they have a complete or partial hearing loss must rely on visual or tactile sig nals to warn them in the event of an emergency. However, consumers rep ort that personal smoke detector devices which provide a visual alarm do not wake people reliably. We examined the ability of visual alertin g devices to wake people from the deepest stages of sleep: slow wave s leep (SWS) and rapid-eye-movement sleep (REM). These results were rela ted to the physical (optical) characteristics of devices currently on the market. In Experiment 1, a range of strobe intensities and locatio ns were investigated. Experiment 2 confirmed the results of this pilot study on an independent set of subjects. On each trial, the strobe wa s allowed to run at a constant intensity until the subject awoke, or a maximum of 5 min had elapsed. Even though a diffuse light remained di rectly over the subject's face for each trial, subjects did not wake c onsistently. Under the favorable optical (smoke-free) conditions of th e present study, the most intense of the devices presently offered for sale in Canada cannot be relied on to wake a sleeping person in the e vent of a fire. It remains unclear whether any visual alerting device can be expected to safely wake a sleeper in an emergency situation.